Cases of two different types of severe diarrhea-causing illnesses are on the rise in the United States. Rotavirus and drug-resistant shigella bacteria aren’t the most common causes of diarrheal illness in the country, but the increasing rates are concerning, according to infectious disease doctors.
“Norovirus is still the king of diarrheal illness,” says Thomas Russo, MD, chief of infectious diseases at the University at Buffalo in New York. “But there are many others that can make you miserable.”
Rotavirus mostly impacts children, and it can be life-threatening, while drug-resistant shigella primarily affects adult men and can lead to hospitalization in 1 out of 3 cases.
Here’s how to know what may be behind a case of diarrhea, plus how to get relief and avoid the worst outcomes.
Rotavirus and Drug-Resistant Shigella Numbers Are Climbing
If you develop intense diarrhea caused by a germ, it’s most likely the result of the highly contagious norovirus, often erroneously referred to as “stomach flu” (norovirus is unrelated to the influenza virus).
“Norovirus is by far and away now the leading cause of infectious diarrhea in the country,” says William Schaffner, MD, an infectious disease specialist and professor at Vanderbilt University School of Medicine.
But rotavirus and drug-resistant shigella cases are swirling around more than before.
Data from WastewasterSCAN, which is a partnership program with Stanford University and Emory University that analyzes wastewater for pathogens, show that cases of rotavirus have been on the rise across the country since January. Many areas around the United States now have levels of rotavirus listed as “high” by the program’s standards.
A recent report from the Centers for Disease Control and Prevention (CDC) noted that cases of “extensively” drug-resistant shigella increased 8.5 percent in the country from 2011 to 2023. These infections don’t respond well to treatment from the common antibiotics ampicillin, azithromycin, ceftriaxone, ciprofloxacin, and trimethoprim-sulfamethoxazole, per the report.
Vaccines to Prevent Rotavirus Are Underutilized
The current vaccine to protect against rotavirus was released in 2006. Since then, 40,000 to 50,000 hospitalizations of infants and young children due to rotavirus are prevented each year, CDC data reveals. Nine out of 10 children who receive the vaccine (typically getting the first dose when they are 2 months old) will be protected from severe disease.
“Vaccination levels are suboptimal and may be driving the number of cases,” says Amesh A. Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security. While rotavirus cases once “plummeted” due to the vaccine, “if children aren’t getting protected, the likelihood of an increasing number of cases is a reality,” Russo says.
There is no approved vaccine in the United States to protect against shigella.
How to Know What’s Behind Your Diarrhea
While both infections cause diarrhea, there may be some differences in the way people experience each. “Shigella causes dysentery — intestinal inflammation — with fevers and mucus-laden diarrhea with abdominal pain, while rotavirus causes diarrhea that does not have these features,” Dr. Adalja says.
Anyone can be infected with either illness, but rotavirus is most common in children, while drug-resistant shigella is more common in men who have sex with men, Adalja says.
It can still be difficult to know what’s behind your diarrhea, especially given that norovirus, salmonella, and other diarrhea-causing microbes are out there as well, Russo says.
What to Do if You Get Sick
Dehydration is the biggest concern with all diarrhea-causing infections, Russo says. That’s why he recommends drinking plenty of fluids, including drinks that contain electrolytes. “If you’re also vomiting, you’ll need to take small sips to try to get something down,” he says. “If it’s just diarrhea, it’s easier to keep up with hydration.”
In most cases, maintaining fluids should help patients ride out the illness, Dr. Schaffner says. (While shigella typically goes away on its own, severe cases may be treated with antibiotics, although effective options are limited for this illness.) But Schaffner recommends monitoring yourself or your family members for symptoms of dehydration.
“You should be vigilant for signs of dehydration — dry mouth, lightheadedness, confusion,” Russo says. If those surface in you or your child, he says it’s important to seek medical care. However, if you have a chronic underlying illness, Schaffner recommends contacting a healthcare provider right away.
Even if you’re well hydrated, it’s still a good idea to consult a healthcare provider if your diarrhea lasts for more than seven days, according to Russo. Your doctor will likely want to evaluate you for possible causes that may require treatment, he says.
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